Unit 7: Topic 4 - Population Genetics Flashcards
How do mutations contribute to evolution?
Mutations can create new alleles (from the altered DNA sequence), creating genetic diversity among a population. A population with greater genetic diversity has a greater chance of survivability and adaptability in changing conditions due to the increased chance of an individual surviving and continuing the population in a disaster. Also, phenotypic frequencies can be altered if the mutation benefits the affected organism, as the advantageous phenotype is naturally selected for.
How does genetic drift contribute to the evolution of a (small) population?
The number of phenotypic alleles in the population that experienced genetic drift will decrease due to the decreased amount of individuals. The remaining alleles in the population would be isolated from other populations’ alleles, altering the phenotypic frequencies forever.
What is a bottleneck and founder effect?
The bottleneck effect is when a population undergoes an event that removes many members (like a mass extinction or a rock slide), which changes phenotypic frequencies and removes alleles from the gene pool. The founder effect is when a small group of members of a population branch off to create a separate population. Similar to a bottleneck, the new (small) population has different phenotypic frequencies and the absence of some alleles, changing the future offspring’s phenotypic frequencies as well. Note: Both are examples of genetic drift.
How does gene flow contribute to evolution?
Gene flow introduces new alleles by moving the locations of a member(s) of a population to another population. The moved member(s) must adapt to the environmental change, leading to evolution. This adds alleles to the population’s gene pool and ultimately drives evolution by the change of phenotypic frequencies because of the possibility for the allele to bring an advantageous trait to a member of the population.
What is a nonselective process, and what are they in evolution?
A nonselective process is one in which evolution occurs primarily due to the fluctuation of phenotypic frequencies in a population(s). Nonselective processes in evolution comprise of gene flow and genetic drift (bottlenecks and founder effect). An example of gene flow and genetic drift is in the attached document. Click here
Why would populations of the same species differ if one of the populations had less genetic variation?
The populations would have differences due to one having a smaller gene pool and thus less phenotypic distribution. In the future, the population with less genetic variation will (most likely) not experience as much change, while the one with greater variation will adapt and evolve more due to its greater gene pool.
What are the sequences of events that lead a mutation to change a population’s phenotypic frequency? Touch on: DNA, offspring, phenotypes, and natural selection.
A mutation first affects a DNA sequence in an organism. The amino acid the DNA sequence codes for will be different, and the protein it produces will be differently shaped. The DNA will go through transcription and translation if the mutation is not nonsense, producing a different phenotype for the organism. The organism will pass on its genetic information to its offspring if it lives, passing on the mutated code. If the phenotype acquired is advantageous and provides greater fitness, the organisms with the new phenotype will be naturally selected for and, over time, change the phenotypic frequencies of the population to favor the new phenotype. Mutations ultimately increase genetic diversity and, in turn, adaptability.
